Welcome to Healthcaremagic. I read your question carefully and I understand your concern. From the signs and symptoms you prescribe it is a possibility that you have a Pyelonephritis. That was also the suspicion in the ER. I would like to know if you did any lab or imaging studies or did in the ER prescribe medication for further treatment? I also would like to know your age and if you have any chronic disorders that would complicate the treatment like diabetes, chronic lung or heart diseases). This is important because if your diagnosis is confirmed, in some cases there is a necessity for hospital admission. I recommend to you to do the following workup: urinalysis (with microscopic analysis), urine culture, CBC and ultrasound of the kidneys and bladder. Regarding the therapy, if the diagnosis is confirmed and if you will be selected for outpatient treatment, you require initially a vigorous IV or oral fluids, paracetamol for fever and a dose of parenteral antibiotic. Then you need a antibiotic therapy at least 7 days in uncomplicated cases and the recommended first line therapy is ciprofloxacin. I hope my answer was helpful to you. And I wish to you a fast recovery and a good health.